There is increasing evidence supporting dietary and alternative therapies for epilepsy, including the ketogenic diet, modified Atkins diet, and omega-3 fatty acids. Vitamin D is actively under investigation as a potential intervention for epilepsy. Vitamin D is fat soluble steroid which shows promise in animal models of epilepsy. Basic research has shed light on the possible mechanisms by which Vitamin D may reduce seizures, and animal data support the efficacy of Vitamin D in rat and mouse models of epilepsy. Very little clinical data exists to support the treatment of human epilepsy with Vitamin D, but positive findings from preliminary clinical trials warrant larger Phase I and II clinical trials in order to more rigorously determine the potential therapeutic value of Vitamin D as a treatment for human epilepsy.

__From the end of the conclusion section""
"Recently, our group has received an IND for a Phase I study of Vitamin D3 in drug resistant epilepsy to study the safety, preliminary efficacy and potential cardiac benefits of Vitamin D3 5000 IU/day in drug resistant epilepsy."

Note: CBD is extremely good at reducing epilepsy – one brand was named after a girl whose seizures deceases by ~20X after taking CBD (hemp oil). (Had purchased Charlotte's Web Hemp Extract in MCT Oil on Amazon Sept 2015 to relieve pain for my father-in-law)

Several studies have shown a link between vitamin D deficiency and epilepsy. This study includes 60 newly diagnosed idiopathic epilepsy patients and 101 healthy controls (between the ages of 5 and 16). Each group was also divided into two subgroups according to seasonal changes in terms of months of longer versus shorter daylight. We retrospectively evaluated the levels of calcium, phosphorus, alkaline phosphatase, parathyroid hormone, and 25-OH vitamin-D3 in the study participants. Levels below 20 ng/ml were defined as vitamin D deficiency and levels of 20-30 ng/ml as insufficiency. There were no significant differences in age, gender distribution and levels of calcium, phosphorus, alkaline phosphatase and parathyroid hormone between the groups. The level of 25-OH vitamin-D3 in the patient group was significantly lower when compared to the control group (p < 0.05) (14.07 ± 8.12 and 23.38 ± 12.80 ng/ml, respectively). This difference also held true when evaluation was made according to seasonal evaluation (12.38 ± 6.53 and 17.64 ± 1.14 in shorter daylight and 18.71 ± 9.87 and 30.82 ± 1.04 in longer daylight).

There are a variety of idiopathic epilepsy syndromes. Children with idiopathic epilepsy may have generalized or partial seizures.
Many, although not all, idiopathic epilepsy syndromes are benign and the child will eventually grow out of them.
Relatives of a child with idiopathic epilepsy often have a history of seizures.
What are other terms for idiopathic epilepsy?An older term for idiopathic epilepsy is primary epilepsy. The terms “idiopathic epilepsy” and “cryptogenic epilepsy” are sometimes used interchangeably, especially in older books and articles.
What causes idiopathic epilepsy?By definition, there is no apparent underlying cause of idiopathic epilepsy, such as a structural problem with the brain or a metabolic disorder. It is possible that idiopathic epilepsy is caused by tiny abnormalities at the cellular level. We are now learning that many, although not all, idiopathic epilepsy syndromes have an associated genetic component.
In most cases, the exact way in which epilepsy is inherited is unclear. However, some researchers estimate that genes could account for 70% to 90% of the tendency to develop epilepsy.
What epilepsy syndromes are idiopathic?

benign epilepsy of childhood with centrotemporal spikes (BECTS)

childhood epilepsy with occipital paroxysms

benign neonatal familial convulsions

benign neonatal convulsions

benign myoclonic epilepsy in infancy

childhood absence epilepsy

juvenile absence epilepsy

juvenile myoclonic epilepsy

How many other children have idiopathic epilepsy?Idiopathic epilepsy is common; about 30% of childhood epilepsy is idiopathic.
Together, idiopathic and cryptogenic epilepsy account for 55% to 75% of cases of childhood epilepsy.
It is difficult to be precise, because different researchers define these terms differently.
How is idiopathic epilepsy treated?Idiopathic epilepsy is treated with anti-epileptic drugs.
What is the outlook for a child with idiopathic epilepsy?The outlook for a child with idiopathic epilepsy depends on the specific condition and how well the seizures respond to treatment.
Several idiopathic epilepsy syndromes, such as childhood absence epilepsy and BECTS, usually go away on their own.
With other syndromes, though, the child may need to take anti-epileptic drugs all his life.
Elizabeth J. Donner, MD, FRCPC, 2/4/2010

About one percent of Americans have some form of epilepsy, and nearly four percent (1 in 26) will develop epilepsy at some point in their lives. The number of Americans who have epilepsy is greater than the number who have multiple sclerosis, Parkinson's disease, and cerebral palsy combined.

Epilepsy and vitamin D: a comprehensive review of current knowledge Dec 2016, Behind a $42 paywall
Seyed Amir Miratashi Yazdi, Mehdi Abbasi, Seyed Masoud Miratashi Yazdi; DOI: https://doi.org/10.1515/revneuro-2016-0044."In this article, we review the possible relationship between vitamin D and epilepsy from different aspects, including the action mechanism of vitamin D in the central nervous system and ecological and epidemiological findings. We also present the outcome of studies that evaluated the level of vitamin D and the impact of administrating vitamin D in epileptic patients or animal subjects"

See also web

http://www.epilepsy.org.au/resources/for-media/facts-statistics-about-epilepsy has such factoids as:
According to the World Health Organisation, epilepsy is the world's most common serious brain disorder
Epilepsy is more than three times as common as multiple sclerosis, Parkinson’s disease and cerebral palsy
It is commonly thought that epilepsy always involves convulsions.
In fact there are around 40 different types of epilepsy and epilepsy syndromes.

Can Cannabis Treat Epileptic Seizures? Scientific American Jan 2016
"Stories of cannabis’s abilities to alleviate seizures have been around for about 150 years . . "
"The researchers reported the intervention reduced motor seizures at a rate similar to existing drugs (a median of 36.5 percent) and 2 percent of patients became completely seizure free. Additionally, 79 percent of patients reported adverse effects such as sleepiness, diarrhea and fatigue, although only 3 percent dropped out of the study due to adverse events. "